For diabetes treatment, management of the blood glucose level by a patient himself or herself is important for maintaining the blood glucose level in a normal range. Particularly, for a patient of insulin-dependent diabetes, regular measurement of the blood glucose level is essential to maintain the blood glucose level in a normal range. However, it is troublesome to often go to a medical institution for measuring the blood glucose level. Conventionally, therefore, apparatuses which enable the extraction and analysis of blood without going to a medical institution have been proposed. For example, JP-A 2001-74731 discloses a lancing unit and a lancing apparatus as shown in FIGS. 26A and 26B.
The lancing unit 9 shown in FIG. 26A includes a lancet 90 as a lancing member, and a first housing 91A accommodating part of the lancet. The first housing 91A is fixedly fitted to a second housing 91B. As shown in FIG. 26B, the second housing 91B is provided with a test strip 92 and a blood introduction portion 95. The first housing 91A has an opening 91a which is closed by a cover 93 so that a sterilized needle 90a of the lancet 90 can be kept hygienically clean. The first and the second housings 91A and 91B are wrapped by a wrapping member 94 in the form of a bag or case.
The lancing unit 9 having the above-described structure is assembled by setting the needle 90a of the lancet 90 into the first housing 91A after the needle 90a is sterilized and then fixing the first housing 91A to the second housing 91B. With such an assembling method, the sterilization of the lancet 90 can be performed independently without adversely affecting the test piece 92. For example, unlike the above, when the sterilization of the lancet 90 is performed after the lancing unit 9 is completely assembled, a constituent of the test piece 92 may be unduly changed due to the sterilization process. With the above assembling method, however, such a problem can be avoided.
As shown in FIG. 26B, the lancing apparatus 8 includes a housing case 80. The first and the second housings 91A and 91B can be mounted to the apparatus when they are pushed to a front end 80a of the housing case 80. Therefore, the lancet 90 and the test piece 92 can be mounted simultaneously. When the lancet 90 pushes a lancet holder 81 to the right in the figure, a spring 82 is compressed to bring the lancing apparatus 8 into a locked state. Thereafter, when an operation switch 83 is operated with the lancing apparatus 8 pressed against the skin of a human body, the lancet holder 81 and the lancet 90 advance to the left in the figure due to the resilient force of the spring 82, whereby the needle 90a of the lancet 90 lances the skin of the human body. The blood bleeding from the skin as a result of the lancing is introduced to the test sheet 92 through the blood introducing portion 95. The blood can be analyzed by optically detecting the color reaction of the test piece 92.
However, the above-described prior art arrangement has the following problems.
First, in the prior art arrangement, to mount the lancet 90 and the test piece 92 to the lancing apparatus 8, both of the first and the second housings 91A and 91B of the lancing unit 9 need be mounted to the lancing apparatus 8. Therefore, the front end of the lancing apparatus 8 needs to be made relatively large. As a result, the size of the lancing apparatus 8 increases, which is inconvenient for carrying.
Secondly, from a hygienic point of view, the needle 90a of the lancet 90 need be hermetically sealed in the first housing 91A of the lancing unit 9. For this purpose, the portion where the first housing 91A and the lancet 90 are fitted together need be hermetically sealed. On the other hand, after the first housing 91A along with the lancet 90 is mounted to the lancing apparatus 8 and the lancet holder 81 is advanced, the lancet 90 needs to move smoothly relative to the first housing 91A in accordance with the movement of the lancet holder. However, to hold the lancet 90 in the first housing 91A in such a manner as to satisfy the above two requirements is not easy. Thus, the needle 90a of the lancet 90 sometimes is not hermetically sealed, or the lancet 90 after it is mounted to the lancing apparatus 8 sometimes does not move smoothly.
Thirdly, in the lancing apparatus 8, it is desirable that the blood introduction portion 95 is located as close to the lancing position as possible. This is because, as the blood introduction portion 95 is farther from the lancing position, the blood is less likely to come into contact with the blood introduction portion 95 properly. Even when the blood comes into contact with the blood introduction portion 95, the amount of blood reaching the test piece 92 is small, whereby accurate analysis result may not be obtained. Since the first case 91A is fixed to the housing 80 while the lancet 90 moves reciprocally along a predetermined path, the distance s between the path and the blood introduction portion 95 is always constant. In the prior art arrangement, therefore, to locate the blood introduction portion 95 close to the lancing position, the blood introduction portion 95 need be provided close to the needle 90a of the lancet 90 in the state of the lancing unit 9 shown in FIG. 26A (though this figure does not show the blood introduction portion). However, in actually designing and manufacturing the lancing unit 9, various points need be taken into consideration such as reduction in size of the entire unit and the airtightness of the first case 91A, so that it is sometimes difficult to locate the blood introduction portion 95 sufficiently close to the needle 90a of the lancet 90. Therefore, in the prior art arrangement, it is difficult to locate the blood introduction portion 95 sufficiently close to the lancing position, so that the amount of blood introduced to the test piece 92 is sometimes insufficient.
Fourthly, since the lancing unit 9 requires the cover 93 in addition to the first and the second housings 91A and 91B, the number of parts of the lancing unit 9 is large, whereby the manufacturing cost is relatively high.